X Spoked Wheels and twin discs on a Monolever Bitsa.

I’ve taken measurements for a new centre spacer but the stock monolever right side outer spacer looks it might be plug and play.

The wheel looks centred between the forks but I need to get a vernier on it to be sure.

If it is the correct width I need to measure up for a left side spacer to get the wheel permanently fitted.

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Stirlingmoz
 
Thanks Stirling - this is interesting. So this is an R80G/S front end and an 18" R1200C front wheel. Will the discs and calliper line up is the obvious next question.

I'll be experimenting with a test fit of an R100R 41mm twin disc front end and my R80ST bitsa over Christmas.
 
Thanks Stirling - this is interesting. So this is an R80G/S front end and an 18" R1200C front wheel. Will the discs and calliper line up is the obvious next question.

The honest answer is I don’t know yet.

I’m going to use the disc mounting faces to centre the wheel in the forks as step 1.

I’m hoping I can modify stock outer spacers to achieve this.

I’m resigned to having to commission a custom centre spacer.

After that I can offer up a caliper and see where we are.

Good luck with your mods.

Stirlingmoz
 
So I’ve hit a problem.

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The brake disc mounting bolts hit the inside of the lower fork leg.

All my careful measuring - but I hadn’t foreseen this.

Not sure if I can make this work now.

I’m considering my options.

Stirlingmoz
 
I like the overall look of 300mm brake discs but the set up might not actually work unless I can come up with a solution

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Stirlingmoz
 
I like the overall look of 300mm brake discs but the set up might not actually work unless I can come up with a solution

Stirlingmoz
Lose the floating buttons. I've done some machining & run countersunk allen headed bolts into the hub. You can also machine the legs that hold the Disc quite a ways back too. I've done this on my R100GS sidecar with WP4860 forks. The spacing for the triples was to allow use on an R80G/S. I used a monolever axle for that too. But I only run one disc https://www.advrider.com/f/threads/playing-with-the-chair.1090132/page-21
 
Thank you for the reply.

Really useful info there.

I have already ordered some allen bolts with ultra thin heads.

I can see there’s quite a lot of meat on the bobbins too.

I had looked at the legs that the discs bolt up to to but wondered if this would then go on to affect brake caliper location ?

I also wondered how thick the fork lowers are and if I could shave a small (short and shallow) channel out to allow the bolts to pass ?

I’m liking your countersunk bolt solution at the moment. This solution preserves wheel, brake disc and fork leg integrity.
 
Still working to get the R1200C wheel in the monolever forks and made some progress.

Decided to lose the floating discs and solidly mount them using ultra low profile allen bolts.

That gained me about 3mm.

Got a modified front axle - it’s the rear one and a stock monolever for comparison.

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The discs are 122mm apart (side to side). Stock monolever discs are 120mm.
Measurements from the centre of disc width.

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To gain a little more clearance I’m going to face the disc mounts on the hub by 1mm.

This will also return the disc to caliper orientation to stock monolever.

Hoping this will give me a working clearance and make caliper fitment more straightforward.
 
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Great that you're making progress Stirling - looks tough going. Remind me again please on the objective here - wouldn't an 18" R100R wheel have been a lot easier to fit?
 
Hi Doc..You’re absolutely right. An R100R front wheel and stock 285mm brake discs would be plug and play.

However I was trying to run a similar looking wheel but with 300mm brake discs and Brembo 4 piston calipers. A subtle brake upgrade is the goal I guess.

The other thing is that I’ve not seen it done before - so it’s a bit of a challenge.
 
First mock up of the Brembo 4 piston brake calipers mounted on monolever forks.

Good match for the R1200 wheel and it’s 300mm brake discs.

One thing I was worried about was the clearance between the back of the brake caliper and the spokes. Luckily there’s loads of room.

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Stirlingmoz
 
After a very very long part search and a couple of months of waiting, my airhead biSTa wheels are back and wow - they look absolutely amazing, even if I do say so myself.

R100GS rear hub machined down to allow fitment to a mono 4 stud final drive - blasted and powder coated gloss black (Yes Mikey Boy, this is the hub that I bought from you a long long long time ago!)
R100GS 17" rear rim - blasted and powder coated gloss black
15mm offset wheel build with HD stainless spokes

R100R twin disc front hub (still not sure if there's a difference between single and twin disc hubs but this one is a twin) - blasted and powder coated gloss black
R1150GS 19" - blasted and powder coated gloss black
HD stainless spokes

The parts were pretty rough when supplied to the wheel builder - many had been sitting around for 20+ years. The R1150GS rim sat outside my front door for about 15 years. All parts now look like new, in fact better than new. Absolute top quality work from a proper old school engineer.

Now to fit them - that can't happen until the weekend after Easter as the bike lives at my in-laws house - which is one of the reasons that this project has taken sooooooooooooo long.

TKC70 tyres to be ordered - standard front, rock :)cool) rear in a mighty 130 section spec.

I really really really hope these fit.

Next on the list is rebuild and fit my R100R forks and buy a proper rear shock. Any info on what high front mudguard to use would be appreciated too please.

Getting there - or at least getting somewhere :thumb
 

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I would recommend that you skim the rear brake drum.

Get a nice smooth operating and efficient rear brake.

I did mime, approx 10 thou, made all the difference in the world.
 
Looking really good Alf - can’t wait to see it finished!
I am bowled over by the skills of some of the folk on here:bow:bow

All credit to Doug Richardson - the master wheel builder. I just collected a few parts and placed the order!

I would recommend that you skim the rear brake drum.

Get a nice smooth operating and efficient rear brake.

I did mime, approx 10 thou, made all the difference in the world.

I'm not planning on going fast enough to need brakes. Good info though - thanks:thumb
 
Progress – A long weekend at the in-laws (where the bike lives) and I’ve started to make progress on the ST bitsa pyg. R100R forks fitted, wheels fitted, single seat installed. Starting to come together. Loads of problems encountered and loads more work to do but at least it’s on its wheels (kind of) and gives an idea of what the thing will look like when completed. Plan is to fit a proper rear shock which will be G/S spec so slightly longer than the ST unit which will raise the rear a little and level things out – I can also drop the R100R forks through the clamps a little. Forks still need to be rebuilt – this was just a test fit really. Front end is all good – R100R front end bolts straight on to an ST (mono) frame. Twin oilhead spec front brakes from the R100R will be massive overkill but that’s fine.

Rear wheel was a bit of a faff. I’d bought the hub pre-machined so didn’t have the original measurements available. Turns out it’s been machined slightly too much and now rubs - which isn’t a massive problem as I can use a shim to correct. I think my hub had been machined down by 20mm – I now know that the correct amount is 17mm. I’m running a 130 section TKC70 Rocks tyre with a 15mm offset rear wheel which easily clears the swingarm. I’m led to believe that that there is a small amount of adjustment available in the swingarm – but only maybe 3mm. Once the shim is installed and the swingarm is tweaked, we’ll be good to go. The main issue that I’ve got is that the wheels are now out of alignment by - have a guess…. 15mm - which obviously makes sense when you think about it. I suspect this can be reduced to more like 10mm but the wheels still won’t be in true alignment. Having read up on this – I believe this is normal for the cross spoke modification but it still hurts my OCD a little. We’ll see what it rides like when it’s all together later in the year. Hopefully I haven’t spent years and ££££ building a crab bike.

Still need to sort out a front mudguard – I’ll put a separate post up asking for recommendations.

Looks like this
 

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